Beliefs in mysterious underworlds are as old as humanity. But the idea that the earth has a hollow interior was first proposed as a scientific theory in 1691 by Sir Edmond Halley (of comet fame), who also suggested that there might be life down there as well. Hollow Earth traces the many surprising, marvelous, and just plain weird permutations his ideas have taken over the centuries. Both Edgar Allan Poe and (more famously) Jules Verne picked up the torch in the nineteenth century, the latter with his science fiction epic A Journey to the Center of the Earth. The notion of a hollow earth even inspired a religion at the turn of the twentieth century-Koreshanity, which held not only that the earth was hollow, but also that we’re all living on the inside. Utopian novels and adventures abounded at this same time, including L. Frank Baum’s hollow earth addition to the Oz series and Edgar Rice Burroughs’s Pellucidar books chronicling a stone-age hollow earth. In the 1940s an enterprising science-fiction magazine editor convinced people that the true origins of flying saucers lay within the hollow earth, relics of an advanced alien civilization. And there are still devout hollow earthers today, some of whom claim there is a New Age utopia lurking beneath the earth’s surface, with at least one entrance near Mt. Shasta in California. Hollow Earth travels through centuries and cultures, exploring how each era’s relationship to the idea of a hollow earth mirrored its hopes, fears, and values. Illustrated with everything from seventeenth-century maps to 1950s pulp art to movie posters and more, Hollow Earth is for anyone interested in the history of strange ideas that just won’t go away.